JP4477344B2 - Zoom lens and image pickup apparatus including the same - Google Patents

Description

  INDUSTRIAL APPLICABILITY The present invention is suitable for a zoom lens used in a lens interchangeable single lens reflex type in a photographic camera or an electronic still camera. The present invention relates to a lens and an imaging apparatus including the lens.

  Conventionally, many wide-angle zoom lenses arranged in order of the negative lens group and the positive lens group from the object side have been proposed. This is because, in a TTL single-lens reflex type camera often used for an interchangeable lens camera, a mirror movable space or a beam splitter arrangement space is required on the object side of the imaging plane. However, the retro focus type arrangement of the negative lens group and the positive lens group is an effective means for achieving sufficient back focus.

In particular, in a super wide-angle zoom lens whose field angle reaches about 100 °, a back focus far exceeding the actual focal length is required. For this reason, it is difficult to correct aberrations satisfactorily with a retrofocus zoom lens having a simple configuration in which the negative lens group and the positive lens group are arranged in this order. Therefore, for example, various super wide-angle zoom lenses in which the positive lens group is composed of a plurality of groups as shown in the following Patent Documents 1 to 4 have been proposed.
Japanese Patent No. 3284784 JP 2000-221399 A JP 2001-83421 A JP 2002-287031 A

  However, the super wide-angle zoom lenses according to the inventions disclosed in these patent documents have a back focus of about 2 to 2.5 times the actual focal length at the short focal length end, and further shorten the focal length. There was a problem that the back focus could not be sufficiently obtained when pursuing the development. Further, when considering application to an optical apparatus that requires a longer back focus, there has been a restriction that the conventional optical system cannot be used.

  The present invention has been made in view of the above problems, and in an ultra-wide angle zoom lens having an angle of view exceeding 100 ° at the short focal length end, the focal length can be shortened and the back focus can be increased. An object of the present invention is to provide an ultra-wide-angle zoom lens having good optical performance over the entire zooming range and an imaging apparatus including the same.

To achieve the above object, a zoom lens according to the present invention, and in order from the object side, Te formed Ttei from a front group, and a rear group having a positive refractive power as a whole having a negative refractive power as a whole, At the time of zooming, the air gap between the front group and the rear group is changed, and the rear group has a second lens group having positive refractive power as a whole in order from the object side, and an aperture stop. The second lens group includes a third lens group including a cemented lens and a fourth lens group having a positive refractive power as a whole, and each of the air in the second to fourth lens groups during zooming. Further, the second lens group is composed of a second lens group first subunit and a second lens group second subunit in order from the object side, and at the time of zooming. The second lens group first subunit and the second lens group second subunit; A configuration in which the air interval is not changed, or further, the second lens group includes, in order from the object side, a second lens group first subunit having a positive refractive power as a whole and a negative single lens. And a second lens group second subunit, and an air gap between the second lens group first subunit and the second lens group second subunit is changed during zooming. There is a zoom lens in which the group whose group interval changes upon zooming is 4 or 5, and the final lens group arranged closest to the image plane of the rear group has two cemented surfaces and has a cemented lens consisting of three lenses, a positive lens is configured by arranging at least one each of the object side and the image side of the cemented lens, as a feature that you satisfy the following condition (2) Yes.
0.5 <| ΦIII / ΦL | <1.7 (2)
Where ΦIII is the refractive power of the cemented lens composed of the three lenses having the two cemented surfaces, and ΦL is the refractive power of the final lens group.

The zoom lens according to the present invention satisfies the following conditional expression (1).
0.18 <1 / (1-dfrw × Φfw + Φw × hrw) <0.30 (1)
Where Φw is the refractive power of the entire system at wide angle, Φfw is the refractive power of the front group at wide angle, dfrw is the distance between the main point of the front group and the main point of the rear group at wide angle, and hrw is after the wide angle This is the rear principal point position of the group.

The zoom lens according to the present invention satisfies the following conditional expression (2 ′) .
0.7 <| ΦIII / ΦL | <1.5 (2 ′)

  In the zoom lens of the present invention, the front group includes, in order from the object side, a first negative meniscus lens having a convex surface facing the object side and a second surface having a convex surface facing the object side having at least one aspheric surface. It is characterized by comprising a first subunit composed of a negative meniscus lens, and a second subunit comprising at least one positive lens and at least one negative lens.

Further, in the zoom lens of the present invention, before Symbol second lens group comprises, in order from the object side, first and second lens group first subunit having a positive refractive power as a whole, composed of a negative single lens It is composed of two lens group second subunits, and is characterized in that the air gap between the second lens group first subunit and the second lens group second subunit is changed during zooming.

  In the zoom lens according to the present invention, the last lens group includes, in order from the object side, a positive single lens having at least one aspheric surface, a negative lens, a biconvex lens, and a negative lens, and has two diverging surfaces. It is characterized by comprising a cemented lens and a positive single lens.

In the zoom lens according to the present invention, the following conditional expression (5) is satisfied.
0.60 <f1_w / IH <0.83 (5)
However, f1_w is the focal length at the short focal length end, and IH is the image height.

In addition, an image pickup apparatus including the zoom lens according to the present invention includes any one of the zoom lenses according to the present invention and an image pickup portion that determines an image pickup region arranged on the image side .
Also, the zoom lens according to the present invention is characterized by satisfying the following condition (3).
0.45 <| Φu1 / Φfw | <1.0 (3)
Where Φu1 is the refractive power of the first subunit, and Φfw is the refractive power of the front group at a wide angle.
The zoom lens according to the present invention satisfies the following conditional expression (4).
−0.5 <(r2f−r2r) / (r2f + r2r) <0.2 (4)
Here, r2f is the radius of curvature of the lens surface closest to the object side of the second lens group, r2r is the radius of curvature of the lens surface closest to the image side of the second lens group, and 0 <r2f and 0 <r2r .
Also, the zoom lens according to the present invention is characterized by satisfying the following condition (1 ').
0.20 <1 / (1-dfrw × Φfw + Φw × hrw) <0.25 (1 ′)
Where Φw is the refractive power of the entire system at wide angle, Φfw is the refractive power of the front group at wide angle, dfrw is the distance between the main point of the front group and the main point of the rear group at wide angle, and hrw is after the wide angle This is the rear principal point position of the group .
Also, the zoom lens according to the present invention is characterized by satisfying the following condition (3 ').
0.5 <| Φu1 / Φfw | <0.9 (3 ′)
Where Φu1 is the refractive power of the first subunit, and Φfw is the refractive power of the front group at a wide angle.
The zoom lens according to the present invention satisfies the following conditional expression (4 ′).
−0.4 <(r2f−r2r) / (r2f + r2r) <0.1 (4 ′)
Here, r2f is the radius of curvature of the lens surface closest to the object side of the second lens group, r2r is the radius of curvature of the lens surface closest to the image side of the second lens group, and 0 <r2f and 0 <r2r .
The zoom lens according to the present invention satisfies the following conditional expression (5 ′).
0.63 <f1_w / IH <0.75 (5 ′)
However, f1_w is the focal length at the short focal length end, and IH is the image height.

  According to the present invention, in a super wide-angle zoom lens having an angle of view exceeding 100 ° at the short focal length end, the focal length can be shortened and the back focus can be made long, and good optical performance over the entire zoom range. An ultra-wide-angle zoom lens having performance and an imaging apparatus including the same can be obtained.

Prior to the description of the embodiments, the effects of the present invention will be described.
A retro-focus type group configuration is a conventionally well-known technique as a design method for obtaining a long back focus. In order to ensure the back focus with a two-group configuration of lens groups having negative and positive refractive power while satisfying the desired specifications, the refractive power of the preceding negative lens group should be increased, or the distance between the front group and the rear group Is enough.
However, when the refractive power of the negative lens group is increased, the refractive power of the positive lens group must be increased accordingly. As a result, residual aberrations in each lens group cannot be completely removed, making it difficult to correct aberrations. In addition, increasing the distance between the front group and the rear group directly leads to an increase in the overall length, and for an optical system with a wide angle of view such as a camera lens, the effective diameter is significantly increased and the lens size is increased. I will wake you up.
Therefore, in the zoom lens of the present invention, in order to solve these problems, the rear group is composed of two or more positive lens groups.

In the retrofocus type optical system, the power distribution of the front and rear groups centering on the aperture stop when viewed from the whole optical system is asymmetrical, so various aberrations such as coma flare and lateral chromatic aberration generated in the front group are It is an optical system that is not easy to correct. For this reason, in the retrofocus type optical system, in order to perform good aberration correction, it is particularly necessary to take a complicated configuration for the final lens group.
However, in the zoom lens according to the present invention, the final lens group is configured to include a cemented lens including three lenses for aberration correction. This is mainly intended to correct lateral chromatic aberration generated in the front group. In order to obtain a sufficient chromatic aberration effect, a single cemented surface is insufficient in the final lens group. For this reason, a three-lens cemented lens is used as a means having two cemented surfaces. With this configuration, it is possible to satisfactorily correct lateral chromatic aberration within the cemented surface, reduce performance deterioration due to assembly variations, and further improve the assemblability of the lens.

  Further, the final lens group bears most of the zooming action of the optical system and requires a considerable amount of refractive power. For this reason, in the zoom lens of the present invention, at least one positive lens is disposed on the object side and the image side of the cemented lens for the purpose of achromatic effect. In this way, a desired refractive power in the final lens group can be obtained through these positive lenses, and an effect of correcting coma flare and the like while suppressing the occurrence of chromatic aberration can be obtained.

In the zoom lens according to the present invention, the paraxial structure at the short focal length end is configured to satisfy the following conditional expression (1).
0.18 <1 / (1-dfrw × Φfw + Φw × hrw) <0.30 (1)
Where Φw is the refractive power of the entire system at wide angle, Φfw is the refractive power of the front group at wide angle, dfrw is the distance between the main point of the front group and the main point of the rear group at wide angle, and hrw is after the wide angle This is the rear principal point position of the group.
If the lower limit value of conditional expression (1) is surpassed, the negative refractive power of the front group becomes extremely large as a result, and distortion, coma aberration, lateral chromatic aberration, etc. cannot be corrected, and a good image cannot be obtained. Further, as the refractive power of the front group increases, the diameter of the front lens becomes remarkably large, causing an increase in the size of the optical system. Further, the principal point position of the rear group is arranged on the image side, and the asymmetry of the structure of the rear group becomes strong, making it difficult to correct aberrations with a small number of sheets.
On the other hand, if the upper limit value of conditional expression (1) is exceeded, an optical system with a sufficiently long back focus, which is the object of the present invention, cannot be achieved.
In the zoom lens of the present invention, the lower limit value of conditional expression (1) may be 0.20.
In the zoom lens of the present invention, the upper limit value of conditional expression (1) may be 0.25.

In the zoom lens of the present invention, it is preferable that the paraxial structure at the short focal length end is configured to satisfy the following conditional expression (2).
0.5 <| ΦIII / ΦL | <1.7 (2)
Where ΦIII is the refractive power of the cemented lens composed of the three lenses having the two cemented surfaces, and ΦL is the refractive power of the final lens group.
If the aberration is sufficiently corrected to fall below the lower limit value of conditional expression (2), the total length of the final group becomes too long.
On the other hand, if the upper limit of conditional expression (2) is exceeded, it will be difficult to correct chromatic aberration.
In the zoom lens of the present invention, the lower limit value of conditional expression (2) may be 0.7.
In the zoom lens of the present invention, the upper limit value of conditional expression (2) may be 1.5.

  As a more preferable configuration of the front lens group in the zoom lens according to the present invention, in order from the object side, a first negative meniscus lens having a convex surface facing the object side and a convex surface facing the object side having at least one aspheric surface. It is preferable to form a first subunit composed of two negative meniscus lenses and a second subunit having at least one positive lens and at least one negative lens.

In the case of a wide-angle lens, the peripheral light amount is reduced by the cosine fourth power law. For this reason, in the case of a super-wide-angle lens with an angle of view exceeding 100 °, peripheral light reduction becomes a problem even if the aperture efficiency is 1.
However, in the zoom lens according to the present invention, if the first lens and the second lens are composed of negative lenses, particularly negative meniscus lenses having a convex surface facing the object side, pupil aberration is greatly generated, and an aperture efficiency of 1 or more is secured. A decrease in the amount of ambient light can be suppressed.

Further, as a problem of the retrofocus type, there is generation of aberration due to asymmetry of the optical system, particularly generation of distortion.
However, in the zoom lens of the present invention, if the second lens is configured to have an aspheric surface, distortion can be corrected efficiently.

  Further, the front group needs a strong divergent refractive power in order to secure the back focus and shorten the total length. Therefore, although a considerable amount of aberration occurs, at least one surface of the first negative meniscus lens having a convex surface directed toward the object side in order from the object side as described above, as in the zoom lens of the present invention. A second subunit having a first subunit composed of a second negative meniscus lens having a convex surface facing the object side having an aspherical surface, at least one positive lens and at least one negative lens With this configuration, it is possible to suppress distortion and peripheral darkening mainly in the first subunit and correct other aberrations appropriately in the second subunit. In the second subunit, a positive lens is particularly required for correcting the Petzval sum.

In the zoom lens according to the present invention, it is preferable that the following conditional expression (3) is satisfied.
0.45 <| Φu1 / Φfw | <1.0 (3)
Where Φu1 is the refractive power of the first subunit, and Φfw is the refractive power of the front group at a wide angle.
If the upper limit of conditional expression (3) is exceeded, it will be difficult to correct off-axis aberrations at angles of view exceeding 100 ° with the two lenses, the first lens and the second lens. Further, increasing the number of lenses is not preferable because the front lens diameter is remarkably increased.
On the other hand, if the lower limit of conditional expression (3) is not reached, it will be difficult to correct aberrations in the first subunit.
In the zoom lens of the present invention, the lower limit value of conditional expression (3) may be 0.5.
In the zoom lens of the present invention, the upper limit value of conditional expression (3) may be 0.9.

In the four-group zoom type zoom lens according to the present invention, the rear group includes a second lens group having a positive refractive power as a whole in order from the object side, and a cemented lens having an aperture stop. The third lens group includes a fourth lens group having a positive refractive power as a whole.
If the second lens group is configured with positive refractive power as in the present invention, there is an effect of moving the entrance pupil position to the object side, thereby shortening the front lens system. In addition, the second lens group and the fourth lens group share the positive refractive power of the rear group, thereby reducing the occurrence of aberrations. In addition, if a stop is disposed in the third lens group located substantially at the center on the optical axis of the rear group, the diameter in the rear group can be shortened. In addition, the surface in the vicinity of the stop has a great influence on spherical aberration and axial chromatic aberration, but if the third lens group is composed of a cemented lens, spherical aberration and axial chromatic aberration can be corrected well with a simple configuration. Can do.

In the zoom lens according to the present invention, it is preferable that the following conditional expression (4) is satisfied.
−0.5 <(r2f−r2r) / (r2f + r2r) <0.2 (4)
However, 0 <r2f and 0 <r2r
R2f is the radius of curvature of the lens surface closest to the object side of the second lens group, and r2r is the radius of curvature of the lens surface closest to the image side of the second lens group.
If the conditional expression (4) is satisfied, it is easy to ensure the symmetry of the power arrangement with the aperture stop as the center when viewed only in the rear group, and it becomes easy to correct aberrations with a small number of lenses.
In the zoom lens of the present invention, the lower limit value of conditional expression (4) may be set to −0.4.
In the zoom lens of the present invention, the upper limit value of conditional expression (4) may be 0.1.

In the zoom lens according to the present invention, the second lens group is composed of a second lens group first subunit having positive refractive power as a whole and a second lens group second subunit composed of a negative single lens. It is preferable that the air gap between the second lens group first subunit and the second lens group second subunit be changed during zooming.
In this way, the second lens group second subunit composed of the negative lens is brought close to the vicinity of the stop arranged in the third lens at the long focal length end, so that the coma at the long focal length end is approached. Aberration correction can be performed.

In the zoom lens according to the present invention, the final lens group includes, in order from the object side, a positive single lens having at least one aspheric surface, a negative lens, a biconvex lens, and a negative lens, and two diverging surfaces. It is preferable that the lens is composed of a cemented lens having a positive single lens.
If the two cemented surfaces of the cemented lens have a divergent refractive power as in the present invention, an achromatic effect can be obtained.

In addition, if the cemented lens has a negative / positive / negative configuration, the dimensions on the optical axis can be reduced by taking the lens edge compared to the positive / negative / positive configuration, and the optical axis direction of the final lens group Therefore, it is possible to take a movable space at the time of zooming, which is advantageous in terms of aberration correction.
In addition, if the final lens is configured by arranging positive single lenses before and after the cemented lens, the configuration as the final lens group can be greatly simplified, and the configuration of the constituent lenses at the time of assembly of the final lens group can be greatly reduced. Position adjustment becomes easy and assembly accuracy is improved.
If the positive lens on the incident side has an aspherical surface as in the present invention, it is greatly advantageous in correcting spherical aberration and coma aberration that occur largely in the vicinity of the incident surface of the final lens group.

In the zoom lens according to the present invention, it is preferable that the following conditional expression (5) is satisfied.
0.60 <f1_w / IH <0.83 (5)
However, f1_w is the focal length at the short focal length end, and IH is the image height.
Conditional expression (5) defines the ratio between the focal length at the short focal length end and the image height in the zoom lens of the present invention.
If the lower limit value of conditional expression (5) is not reached, the front lens diameter of the front group becomes remarkably large, and distortion, coma aberration, lateral chromatic aberration, etc. cannot be corrected in the current configuration, and a good image cannot be obtained.
On the other hand, if the upper limit value of conditional expression (5) is exceeded, the super wide-angle zoom lens that is the object of the present invention cannot be achieved, and the effectiveness in taking the configuration as in the present invention becomes poor. End up.

In the zoom lens according to the present invention, it is preferable that the following conditional expression (6) is satisfied.
2.0 <Da / Do <4.0 (6)
Where Do is the diameter of the marginal ray bundle in the direction along the plane including the optical axis on the optical axis when the short focal length end is open (the aperture state where the F number is the smallest), and Da is the short focal length end. Is the diameter of the marginal ray bundle in the direction along the plane including the optical axis at the full incident angle of view of 100 ° when the lens is opened (the aperture state where the F number is the smallest), and the diameter when viewed from the optical axis direction. It is.
Conditional expression (6) defines the peripheral light amount at the short focal length end in the zoom lens of the present invention.
If the upper limit value of conditional expression (6) is exceeded, the front lens diameter of the front group becomes remarkably large, and distortion, coma aberration, lateral chromatic aberration, etc. cannot be corrected, and a good image cannot be obtained.
On the other hand, if the lower limit value of conditional expression (6) is not reached, the amount of peripheral light cannot be secured by the super wide-angle zoom lens that is the object of the present invention. That is, the function of the first lens group employed to facilitate securing the amount of light at the periphery in the present invention cannot be fully utilized.
In the zoom lens of the present invention, the lower limit value of conditional expression (6) may be 2.3.
In the zoom lens of the present invention, the upper limit value of conditional expression (6) may be 3.5.

  The image pickup apparatus of the present invention includes the zoom lens of the present invention and an image pickup portion that determines an image pickup area arranged on the image side. In this way, an imaging apparatus having the effects of the zoom lens of the present invention described above can be obtained.

  Embodiments of the zoom lens according to the present invention will be described below with reference to the drawings.

  FIG. 1 is a cross-sectional view along the optical axis showing the optical configuration of a zoom lens according to Example 1 of the present invention, where (a) is a short focal length end, (b) is an intermediate focal length, and (c) is a long focal length. The state at the end is shown. 2A and 2B are diagrams showing spherical aberration, astigmatism, distortion aberration, and lateral chromatic aberration when the zoom lens according to Example 1 is focused at infinity. FIG. 2A is a short focal length end, and FIG. 2B is an intermediate focus. The distance, (c), shows the state at the long focal length end.

The zoom lens according to the first exemplary embodiment includes, in order from the object side, a front group GF having a negative refractive power as a whole and a rear group GB having a positive refractive power as a whole. In the figure, I is an imaging surface.
The front group GF constitutes a first lens group, and is composed of a first subunit G11 and a second subunit G12 in order from the object side.
The first subunit G11 includes a negative meniscus lens L11 having a convex surface directed toward the object side, and a biconcave lens L12.
The second subunit G12 includes a biconcave lens L13, a biconvex lens L14, and a negative meniscus lens L15 having a concave surface facing the object side.

The rear group GB includes, in order from the object side, a second lens group G2 having a positive refractive power as a whole, a third lens group G3 having an aperture stop S and composed of a cemented lens, and a positive refractive power as a whole. And a fourth lens group G4.
The second lens group G2 includes, in order from the object side, a second lens group first subunit G21 having a positive refractive power as a whole and a second lens group second subunit G22.
The second lens group first subunit G21 includes a cemented lens of a biconvex lens L21 and a negative meniscus lens L22 having a concave surface facing the object side, and a positive meniscus lens L23 having a concave surface facing the object side. The second lens group second subunit G22 includes a biconcave lens L24.
The third lens group G3 includes, in order from the object side, an aperture stop S, and a cemented lens of a biconvex lens L31 and a biconcave lens L32.
The fourth lens group G4 includes, in order from the object side, a biconvex lens L41, a cemented lens of a negative meniscus lens L42 having a convex surface directed toward the object side, a biconvex lens L43, and a biconcave lens L44, a biconvex lens L45, and a biconvex lens L46. It consists of and.

During zooming from the short focal length end to the long focal length end, the front group GF moves to the image side, the second lens group G2 narrows the distance from the front group GF, and the second lens group first sub The third lens group G3 moves to the image side together with the aperture stop S and then moves to the object side, and then moves to the object side while increasing the distance between the unit G21 and the second lens group second subunit G22. The group G4 moves to the object side so as to narrow the distance from the third lens group G3.
In the zoom lens of Example 1, aspheric surfaces are provided on both surfaces of the negative meniscus lens L11, both surfaces of the biconcave lens L12, the object side surface of the biconvex lens L31, both surfaces of the biconvex lens L41, and the image side surface of the biconvex lens L46. Yes.

Next, numerical data of optical members constituting the zoom lens of Example 1 are shown.
In the numerical data of Example 1, r ₁ , r ₂ ,... Are the radius of curvature of each lens surface, d ₁ , d ₂ ,... Are the thickness or air spacing of each lens, n _d1 , n _d2,. The refractive index of each lens at the d-line, ν _d1 , ν _d2 ,... Represents the Abbe number of each lens, FNO represents the F number, f represents the focal length of the entire system, fb represents the back focus, and IH represents the image height.
The aspherical shape is expressed by the following equation when the optical axis direction is z, the direction orthogonal to the optical axis is y, the conical coefficient is K, and the aspherical coefficients are A ₄ , A ₆ , A ₈ , A _10. It is represented by
z = (y ² / r) / [1+ {1− (1 + K) (y / r) ² } ^1/2 ]
+ A ₄ y ⁴ + A ₆ y ⁶ + A ₈ y ⁸ + A ₁₀ y ¹⁰
These symbols are common to the following embodiments.

Numerical data 1
Short focal length end Intermediate focal length Long focal length end f 8.15 12.00 17.70
FNO 2.8 2.8 2.8
fb 34.99 43.25 55.22
D10 12.68 4.64 1.00
D15 1.01 4.71 7.23
D17 21.58 10.84 2.46
D21 18.26 7.98 1.00

r ₁ = 89.583 (aspherical surface) d ₁ = 2.70 n _d1 = 1.62299 ν _d1 = 58.12
r ₂ = 12.697 (aspherical surface) d ₂ = 12.02
r ₃ = -1030.840 (aspherical surface) d ₃ = 2.00 n _d3 = 1.78800 ν _d3 = 47.37
r ₄ = 40.738 (aspherical surface) d ₄ = 6.64
r ₅ = -67.211 d ₅ = 2.00 n _d5 = 1.88300 ν _d5 = 40.76
r ₆ = 64.191 d ₆ = 0.20
r ₇ = 40.986 d ₇ = 9.86 n _d7 = 1.63980 ν _d7 = 34.46
r ₈ = -27.752 d ₈ = 2.34
r ₉ = -46.012 d ₉ = 1.80 n _d9 = 1.88300 ν _d9 = 40.76
r ₁₀ = −1052.028 d ₁₀ = D10
r ₁₁ = 50.672 d ₁₁ = 7.90 n _d11 = 1.68893 ν _d11 = 31.07
r ₁₂ = -21.585 d ₁₂ = 1.50 n _d12 = 1.92286 ν _d12 = 18.90
r ₁₃ = -46.383 d ₁₃ = 0.20
r ₁₄ = -265.871 d ₁₄ = 2.77 n _d14 = 1.69895 ν _d14 = 30.13
r ₁₅ = −45.720 d ₁₅ = D15
r ₁₆ = −109.455 d ₁₆ = 1.80 n _d16 = 1.88300 ν _d16 = 40.76
r ₁₇ = 49.527 d ₁₇ = D17
r ₁₈ = ∞ (aperture) d ₁₈ = 1.40
r ₁₉ = 27.864 (aspherical surface) d ₁₉ = 5.68 n _d19 = 1.68893 ν _d19 = 31.07
r ₂₀ = -26.052 d ₂₀ = 1.80 n _d20 = 1.88300 ν _d20 = 40.76
r ₂₁ = 52.918 d ₂₁ = D21
r ₂₂ = 24.693 (aspherical surface) d ₂₂ = 6.15 n _d22 = 1.49700 ν _d22 = 81.54
r ₂₃ = -58.114 (non-spherical) d ₂₃ = 0.20
r ₂₄ = 724.292 d ₂₄ = 1.80 n _d24 = 1.78800 ν _d24 = 47.37
_{r 25 = 21.526 d 25 = 9.38} n d25 = 1.49700 ν d25 = 81.54
r ₂₆ = -22.367 d ₂₆ = 1.80 n _d26 = 1.88300 ν _d26 = 40.76
r ₂₇ = 112.171 d ₂₇ = 0.20
r ₂₈ = 29.568 d ₂₈ = 9.58 n _d28 = 1.49700 ν _d28 = 81.54
r ₂₉ = -31.380 d ₂₉ = 0.20
r ₃₀ = 849.375 d ₃₀ = 3.00 n _d30 = 1.74320 ν _d30 = 49.34
r ₃₁ = −108.950 (aspherical surface) d ₃₁ = fb

Aspheric coefficient surface number K A ₄ A ₆ A ₈ A ₁₀
1 9.0000 2.2064 × 10 ^-6 -9.9726 × 10 ^-10 4.4347 × 10 ^-12 -3.6399 × 10 ^-15
2 -1.9008 4.8983 × 10 ^-5 -1.4855 × 10 ^-7 2.6861 × 10 ^-10 -3.8728 × 10 ^-13
3 0 -1.1306 × 10 ^-5 3.9732 × 10 ^-8 -7.9403 × 10 ^-11 6.3600 × 10 ^-14
4 0 3.1931 × 10 ^-5 1.2372 × 10 ^-7 1.9020 × 10 ^-10 -2.4071 × 10 ^-13
19 0.1289 -2.0047 × 10 ^-6 1.9172 × 10 ^-10 -4.9984 × 10 ^-11 9.1967 × 10 ^-14
22 -0.9351 3.2027 × 10 ^-6 -1.9556 × 10 ^-8 1.0951 × 10 ^-10 -2.4772 × 10 ^-12
23 0 2.3 250 × 10 ^-6 -2.3497 × 10 ^-8 -1.1452 × 10 ^-10 -1.4674 × 10 ^-12
31 0 1.4561 × 10 ^-5 3.1402 × 10 ^-8 -1.3227 × 10 ^-11 3.7783 × 10 ^-13

IH (image height): 11.14

  3A and 3B are cross-sectional views along the optical axis showing the optical configuration of the zoom lens according to Example 2 of the present invention, where FIG. 3A is a short focal length end, FIG. 3B is an intermediate focal length, and FIG. 3C is a long focal length. The state at the end is shown. FIGS. 4A and 4B are diagrams showing spherical aberration, astigmatism, distortion aberration, and chromatic aberration of magnification when the zoom lens according to Example 2 is in focus at infinity. FIG. 4A shows a short focal length end, and FIG. 4B shows an intermediate focus. The distance, (c), shows the state at the long focal length end.

The zoom lens according to the second exemplary embodiment includes, in order from the object side, a front group GF having a negative refractive power as a whole and a rear group GB having a positive refractive power as a whole. In the figure, I is an imaging surface.
The front group GF constitutes a first lens group, and is composed of a first subunit G11 and a second subunit G12 in order from the object side.
The first subunit G11 includes a negative meniscus lens L11 having a convex surface directed toward the object side, and a biconcave lens L12.
The second subunit G12 includes a biconcave lens L13, a biconvex lens L14, and a biconcave lens L15 ′.

The rear group GB includes, in order from the object side, a second lens group G2 having a positive refractive power as a whole, a third lens group G3 having an aperture stop S and composed of a cemented lens, and a positive refractive power as a whole. And a fourth lens group G4.
The second lens group G2 includes, in order from the object side, a second lens group first subunit G21 having a positive refractive power as a whole and a second lens group second subunit G22.
The second lens group first subunit G21 includes a cemented lens of a biconvex lens L21 and a negative meniscus lens L22 having a concave surface directed toward the object side. The second lens group second subunit G22 includes a cemented lens of a biconvex lens L23 ′ and a biconcave lens L24.
The third lens group G3 includes, in order from the object side, an aperture stop S, and a cemented lens of a biconvex lens L31 and a biconcave lens L32.
The fourth lens group G4 includes, in order from the object side, a biconvex lens L41, a negative meniscus lens L42 having a convex surface facing the object side, a cemented lens of a biconvex lens L43 and a biconcave lens L44, and a biconvex lens L45. Yes.

At the time of zooming from the short focal length end to the long focal length end, the front group GF moves to the image side, and the second lens group G2 includes the second lens group first subunit G21 and the second lens group second subunit. Integrated with G22, the distance to the front group GF is once widened and then narrowed, and then moved to the image side. The third lens group G3 together with the aperture stop S once moved to the image side and then moved to the object side. Then, the fourth lens group G4 moves toward the object side so as to narrow the distance from the third lens group G3.
In the zoom lens of Example 2, the aspheric surfaces are provided on both surfaces of the negative meniscus lens L11, both surfaces of the biconcave lens L12, the object side surface of the biconvex lens L31, both surfaces of the biconvex lens L41, and the image side surface of the biconvex lens L45. Yes.

Next, numerical data of optical members constituting the zoom lens of Example 2 are shown.
Numerical data 2
Short focal length end Intermediate focal length Long focal length end f 8.15 11.31 15.69
FNO 4.05 4.07 4.06
fb 34.68 41.22 51.28
D10 5.28 5.33 4.61
D16 20.00 8.24 2.30
D20 16.50 9.23 3.11.
r ₁ = 89.583 (aspherical surface) d ₁ = 2.70 n _d1 = 1.62299 ν _d1 = 58.12
r ₂ = 12.697 (aspherical surface) d ₂ = 12.02
r ₃ = -1030.840 (aspherical surface) d ₃ = 2.00 n _d3 = 1.78800 ν _d3 = 47.37
r ₄ = 40.738 (aspherical surface) d ₄ = 6.74
r ₅ = -67.211 d ₅ = 2.00 n _d5 = 1.88300 ν _d5 = 40.76
r ₆ = 64.191 d ₆ = 0.20
r ₇ = 37.111 d ₇ = 9.40 n _d7 = 1.74950 ν _d7 = 35.28
r ₈ = -34.775 d ₈ = 2.34
r ₉ = −81.925 d ₉ = 1.80 n _d9 = 1.88300 ν _d9 = 40.76
r ₁₀ = 45.044 d ₁₀ = D10
r ₁₁ = 32.038 d ₁₁ = 8.80 n _d11 = 1.74000 ν _d11 = 28.30
r ₁₂ = -19.730 d ₁₂ = 1.50 n _d12 = 1.92286 ν _d12 = 18.90
r ₁₃ = -41.039 d ₁₃ = 2.00
r ₁₄ = 65.000 d ₁₄ = 4.20 n _d14 = 1.48749 ν _d14 = 70.23
r ₁₅ = −56.948 d ₁₅ = 1.80 n _d15 = 1.88300 ν _d15 = 40.76
r ₁₆ = 40.006 d ₁₆ = D16
r ₁₇ = ∞ (aperture) d ₁₇ = 1.40
r ₁₈ = 28.655 (aspherical surface) d ₁₈ = 5.80 n _d18 = 1.68893 ν _d18 = 31.07
r ₁₉ = -20.684 d ₁₉ = 1.60 n _d19 = 1.88300 ν _d19 = 40.76
r ₂₀ = 51.989 d ₂₀ = D20
r ₂₁ = 19.350 (aspherical surface) d ₂₁ = 7.45 n _d21 = 1.49700 ν _d21 = 81.54
r ₂₂ = −42.857 (aspherical surface) d ₂₂ = 0.40
r ₂₃ = 83.881 d ₂₃ = 1.50 n _d23 = 1.88300 ν _d23 = 40.76
r ₂₄ = 20.799 d ₂₄ = 8.80 n _d24 = 1.49700 ν _d24 = 81.54
_{r 25 = -18.099 d 25 = 1.65} n d25 = 1.78800 ν d25 = 47.37
r ₂₆ = 145.000 d ₂₆ = 0.40
r ₂₇ = 140.451 d ₂₇ = 5.80 n _d27 = 1.49700 ν _d27 = 81.54
r ₂₈ = -20.680 (aspherical surface) d ₂₈ = fb

Aspheric coefficient surface number K A ₄ A ₆ A ₈ A ₁₀
1 9.0000 2.2064 × 10 ^-6 -9.9726 × 10 ^-10 4.4347 × 10 ^-12 -3.6399 × 10 ^-15
2 -1.9008 4.8983 × 10 ^-5 -1.4855 × 10 ^-7 2.6861 × 10 ^-10 -3.8728 × 10 ^-13
3 0 -1.1306 × 10 ^-5 3.9732 × 10 ^-8 -7.9403 × 10 ^-11 6.3600 × 10 ^-14
4 0 3.1931 × 10 ^-5 1.2372 × 10 ^-7 1.9020 × 10 ^-10 -2.4071 × 10 ^-13
18 -0.7490 3.6375 × 10 ^-6 2.9519 × 10 ^-9 -1.2015 × 10 ^-10 7.1395 × 10 ^-13
21 -3.2397 4.7032 × 10 ^-5 -5.5153 × 10 ^-8 2.5636 × 10 ^-10 -8.8251 × 10 ^-13
22 -19.0804 -7.7839 × 10 ^-6 1.4237 × 10 ^-7 -7.3094 × 10 ^-10 7.0923 × 10 ^-13
28 -1.5685 -5.9280 × 10 ^-6 5.2227 × 10 ^-8 -2.9500 × 10 ^-11 2.0018 × 10 ^-12

IH (image height): 11.14

  5A and 5B are cross-sectional views along the optical axis showing the optical configuration of the zoom lens according to Example 3 of the present invention. FIG. 5A is a short focal length end, FIG. 5B is an intermediate focal length, and FIG. 5C is a long focal length. The state at the end is shown. 6A and 6B are diagrams illustrating spherical aberration, astigmatism, distortion, and chromatic aberration of magnification when the zoom lens according to Example 3 is in focus at infinity, where FIG. 6A is a short focal length end, and FIG. 6B is an intermediate focus. The distance, (c), shows the state at the long focal length end.

The zoom lens according to the third exemplary embodiment includes, in order from the object side, a front group GF having a negative refractive power as a whole and a rear group GB having a positive refractive power as a whole. In the figure, I is an imaging surface.
The front group GF constitutes a first lens group, and is composed of a first subunit G11 and a second subunit G12 in order from the object side.
The first subunit G11 includes a negative meniscus lens L11 having a convex surface facing the object side, and a negative meniscus lens L12 ′ having a convex surface facing the object side.
The second subunit G12 includes a biconcave lens L13 and a positive meniscus lens L14 ′ having a convex surface facing the object side.

The rear group GB includes, in order from the object side, a second lens group G2 having a positive refractive power as a whole, a third lens group G3 having an aperture stop S and composed of a cemented lens, and a positive refractive power as a whole. And a fourth lens group G4.
The second lens group G2 includes, in order from the object side, a second lens group first subunit G21 having a positive refractive power as a whole and a second lens group second subunit G22.
The second lens group first subunit G21 includes a cemented lens of a biconvex lens L21 and a negative meniscus lens L22 having a concave surface directed toward the object side. The second lens group second subunit G22 includes a cemented lens of a biconvex lens L23 ′ and a biconcave lens L24.
The third lens group G3 includes, in order from the object side, an aperture stop S, and a cemented lens of a biconvex lens L31 and a biconcave lens L32.
The fourth lens group G4 includes, in order from the object side, a biconvex lens L41, a cemented lens of a negative meniscus lens L42 having a convex surface facing the object side, a biconvex lens L43, and a negative meniscus lens L44 ′ having a concave surface facing the object side. And a biconvex lens L45.

At the time of zooming from the short focal length end to the long focal length end, the front group GF moves to the image side, and the second lens group G2 includes the second lens group first subunit G21 and the second lens group second subunit. The third lens group G3 moves to the image side so as to increase the distance from the front group GF integrally with G22, and moves to the object side after passing the intermediate focal length together with the aperture stop S. The group G4 moves to the object side so as to narrow the distance from the third lens group G3.
In the zoom lens of Example 3, the aspherical surfaces are the both surfaces of the negative meniscus lens L11, the image side surface of the negative meniscus lens L12 ′ with the convex surface facing the object side, the object side surface of the biconvex lens L31, both surfaces of the biconvex lens L41, It is provided on the image side surface of the biconvex lens L45.

Next, numerical data of optical members constituting the zoom lens of Example 3 are shown.
Numerical data 3
Short focal length end Intermediate focal length Long focal length end f 7.13 9.90 13.75
FNO 4.03 4.05 4.06
fb 34.307 40.619 50.141
D8 2.80 6.67 8.42
D14 19.00 9.30 2.30
D18 12.81 6.31 1.87

r ₁ = 1619.019 (aspherical surface) d ₁ = 2.70 n _d1 = 1.74320 ν _d1 = 49.34
r ₂ = 18.073 (aspherical surface) d ₂ = 7.35
r ₃ = 49.500 d ₃ = 2.00 n _d3 = 1.80610 ν _d3 = 40.92
r ₄ = 21.524 (aspherical surface) d ₄ = 9.45
r ₅ = −57.800 d ₅ = 2.00 n _d5 = 1.88300 ν _d5 = 40.76
r ₆ = 44.758 d ₆ = 2.35
r ₇ = 24.896 d ₇ = 4.82 n _d7 = 1.67270 ν _d7 = 32.10
r ₈ = 51.555 d ₈ = D8
r ₉ = 27.338 d ₉ = 8.65 n _d9 = 1.84666 ν _d9 = 23.78
r ₁₀ = -22.622 d ₁₀ = 1.50 n _d10 = 1.92286 ν _d10 = 18.90
r ₁₁ = -119.130 d ₁₁ = 1.50
r ₁₂ = 33.825 d ₁₂ = 4.80 n _d12 = 1.48749 ν _d12 = 70.23
r ₁₃ = -22.256 d ₁₃ = 1.50 n _d13 = 1.88300 ν _d13 = 40.76
r ₁₄ = 27.591 d ₁₄ = D14
r ₁₅ = ∞ (aperture) d ₁₅ = 1.90
r ₁₆ = 28.587 (aspherical surface) d ₁₆ = 5.00 n _d16 = 1.68893 ν _d16 = 31.07
_{r 17 = -17.508 d 17 = 1.60} n d17 = 1.88300 ν d17 = 40.76
r ₁₈ = 151.598 d ₁₈ = D18
r ₁₉ = 19.480 (aspherical surface) d ₁₉ = 7.53 n _d19 = 1.49700 ν _d19 = 81.54
r ₂₀ = −28.629 (aspherical surface) d ₂₀ = 0.50
r ₂₁ = 165.671 d ₂₁ = 1.50 n _d21 = 1.88300 ν _d21 = 40.76
r ₂₂ = 15.259 d ₂₂ = 10.00 n _d22 = 1.49700 ν _d22 = 81.54
r ₂₃ = -16.245 d ₂₃ = 1.50 n _d23 = 1.88300 ν _d23 = 40.76
r ₂₄ = -114.496 d ₂₄ = 0.50
_{r 25 = 165.465 d 25 = 6.10} n d25 = 1.51633 ν d25 = 64.14
r ₂₆ = -19.682 (aspherical surface) d ₂₆ = fb

Aspheric coefficient surface number K A ₄ A ₆ A ₈ A ₁₀
1 0 3.6051 × 10 ^-5 -5.8517 × 10 ^-8 4.9736 × 10 ^-11 3.8122 × 10 ^-15
2 -0.3817 -4.3349 × 10 ^-5 3.3049 × 10 ^-7 -1.5662 × 10 ^-9 2.5871 × 10 ^-12
4 0 8.9469 × 10 ^-5 -2.1155 × 10 ^-7 2.5535 × 10 ^-9 -6.5154 × 10 ^-12
16 -2.0431 7.8956 × 10 ^-6 -2.4559 × 10 ^-8 5.1991 × 10 ^-10 -3.5788 × 10 ^-12
19 -4.5805 5.9489 × 10 ^-5 -1.7561 × 10 ^-7 7.6987 × 10 ^-10 -2.0538 × 10 ^-12
20 -3.4963 5.3703 × 10 ^-6 3.8142 × 10 ^-8 -4.8367 × 10 ^-11 -8.2682 × 10 ^-13
26 -1.0488 -5.6314 × 10 ^-6 1.5451 × 10 ^-8 -8.5560 × 10 ^-11 5.6385 × 10 ^-13

IH (image height): 11.14

  7A and 7B are cross-sectional views along the optical axis showing the optical configuration of the zoom lens according to Example 4 of the present invention, where FIG. 7A is a short focal length end, FIG. 7B is an intermediate focal length, and FIG. 7C is a long focal length. The state at the end is shown. FIGS. 8A and 8B are diagrams showing spherical aberration, astigmatism, distortion, and lateral chromatic aberration at the infinity focal point of the zoom lens according to Example 4, where FIG. 8A is a short focal length end, and FIG. 8B is an intermediate focus. The distance, (c), shows the state at the long focal length end.

The zoom lens according to the fourth exemplary embodiment includes, in order from the object side, a front group GF having a negative refractive power as a whole and a rear group GB having a positive refractive power as a whole. In the figure, I is an imaging surface.
The front group GF constitutes a first lens group, and is composed of a first subunit G11 and a second subunit G12 in order from the object side.
The first subunit G11 includes a negative meniscus lens L11 having a convex surface facing the object side, and a negative meniscus lens L12 ′ having a convex surface facing the object side.
The second subunit G12 includes a plano-concave lens L13 ′ having a plane on the object side and a concave surface on the image side, a biconcave lens L14 ″, and a positive meniscus lens L15 ″ having a concave surface facing the object side.
The rear group GB includes, in order from the object side, a second lens group G2 having a positive refractive power as a whole, a third lens group G3 having an aperture stop S and composed of a cemented lens, and a positive refractive power as a whole. And a fourth lens group G4.
The second lens group G2 includes, in order from the object side, a second lens group first subunit G21 having a positive refractive power as a whole and a second lens group second subunit G22.
The second lens group first subunit G21 includes a cemented lens of a biconvex lens L21 and a negative meniscus lens L22 having a concave surface directed toward the object side. The second lens group second subunit G22 includes a cemented lens of a biconvex lens L23 ′ and a biconcave lens L24.
The third lens group G3 includes, in order from the object side, an aperture stop S, and a cemented lens of a biconvex lens L31 and a biconcave lens L32.
The fourth lens group G4 includes, in order from the object side, a biconvex lens L41, a cemented lens of a negative meniscus lens L42 having a convex surface facing the object side, a biconvex lens L43, and a negative meniscus lens L44 ′ having a concave surface facing the object side. And a biconvex lens L45.

In zooming from the short focal length end to the long focal length end, the front group GF once moves to the image side, then moves to the object side, and the second lens group G2 is connected to the second lens group first subunit G21. Integrated with the second lens group second subunit G22, the distance from the front group GF is once widened and then narrowed, and once moved to the image side, then moved to the object side, and then moved to the third lens group G3. Moves along with the aperture stop S toward the object side, and the fourth lens group G4 moves toward the object side so as to narrow the distance from the third lens group G3.
In the zoom lens of Example 4, the aspherical surfaces are formed on both surfaces of the negative meniscus lens L11, the image side surface of the negative meniscus lens L12 ′ with the convex surface facing the object side, both surfaces of the biconvex lens L41, and the image side surface of the biconvex lens L45. Is provided.

Next, numerical data of optical members constituting the zoom lens of Example 4 are shown.
Numerical data 4
Short focal length end Intermediate focal length Long focal length end f 7.13 9.90 13.75
FNO 4.03 4.04 4.04
fb 34.37 41.87 54.01
D10 2.70 3.94 2.30
D16 11.73 5.55 2.30
D20 8.45 3.83 1.00

r ₁ = 212.757 (aspherical surface) d ₁ = 2.70 n _d1 = 1.74320 ν _d1 = 49.34
r ₂ = 21.766 (aspherical surface) d ₂ = 8.80
r ₃ = 61.000 d ₃ = 2.00 n _d3 = 1.80610 ν _d3 = 40.92
r ₄ = 21.489 (aspherical surface) d ₄ = 6.11
r ₅ = ∞ d ₅ = 2.00 n _d5 = 1.88300 ν _d5 = 40.76
r ₆ = 48.459 d ₆ = 3.00
r ₇ = -45.756 d ₇ = 2.50 n _d7 = 1.77250 ν _d7 = 49.60
r ₈ = 56.880 d ₈ = 2.00
r ₉ = -76.431 d ₉ = 4.73 n _d9 = 1.84666 ν _d9 = 23.78
r ₁₀ = −34.222 d ₁₀ = D10
r ₁₁ = 19.592 d ₁₁ = 11.00 n _d11 = 1.61756 ν _d11 = 34.70
r ₁₂ = -22.782 d ₁₂ = 1.50 n _d12 = 1.88300 ν _d12 = 40.76
r ₁₃ = -51.957 d ₁₃ = 1.04
r ₁₄ = 99.550 d ₁₄ = 4.00 n _d14 = 1.48749 ν _d14 = 70.23
r ₁₅ = -22.878 d ₁₅ = 1.50 n _d15 = 1.88300 ν _d15 = 40.76
r ₁₆ = 43.760 d ₁₆ = D16
r ₁₇ = ∞ (aperture) d ₁₇ = 1.90
r ₁₈ = 24.051 d ₁₈ = 5.30 n _d18 = 1.62588 ν _d18 = 35.70
r ₁₉ = -14.390 d ₁₉ = 1.60 n _d19 = 1.88300 ν _d19 = 40.76
r ₂₀ = 63.311 d ₂₀ = d20
r ₂₁ = 19.727 (aspherical surface) d ₂₁ = 7.40 n _d21 = 1.49700 ν _d21 = 81.54
r ₂₂ = -25.844 (aspherical surface) d ₂₂ = 0.30
r ₂₃ = 67.010 d ₂₃ = 1.50 n _d23 = 1.88300 ν _d23 = 40.76
r ₂₄ = 17.750 d ₂₄ = 9.00 n _d24 = 1.48749 ν _d24 = 70.23
_{r 25 = -18.550 d 25 = 1.50} n d25 = 1.88300 ν d25 = 40.76
r ₂₆ = -700.000 d ₂₆ = 0.30
r ₂₇ = 110.629 d ₂₇ = 5.60 n _d27 = 1.58313 ν _d27 = 59.38
r ₂₈ = -21.309 (aspherical surface) d ₂₈ = fb

Aspheric coefficient surface number K A ₄ A ₆ A ₈ A ₁₀
1 0 2.7248 × 10 ^-5 -1.0364 × 10 ^-8 -1.4518 × 10 ^-11 3.0 151 × 10 ^-14
2 0 -2.3471 × 10 ^-5 1.6099 × 10 ^-7 -2.5721 × 10 ^-10 -2.0219 × 10 ^-13
4 0 6.3553 × 10 ^-5 -3.3448 × 10 ^-8 -1.0083 × 10 ^-9 9.0 140 × 10 ^-12
21 -2.9946 2.4976 × 10 ^-5 -1.6638 × 10 ^-8 1.9932 × 10 ^-10 1.9558 × 10 ^-12
22 -2.1536 1.0174 × 10 ^-5 1.7214 × 10 ^-9 -2.5289 × 10 ^-10 4.9094 × 10 ^-12
28 -1.1426 -2.4725 × 10 ^-6 5.0490 × 10 ^-8 -1.6382 × 10 ^-10 1.1272 × 10 ^-12

IH (image height): 11.14

  FIG. 9 is a cross-sectional view along the optical axis showing the optical configuration of a zoom lens according to Example 5 of the present invention, where (a) is a short focal length end, (b) is an intermediate focal length, and (c) is a long focal length. The state at the end is shown. FIG. 10 is a diagram illustrating spherical aberration, astigmatism, distortion, and chromatic aberration of magnification at the time of focusing at infinity of the zoom lens according to Example 5, where (a) is a short focal length end and (b) is an intermediate focus. The distance, (c), shows the state at the long focal length end.

The zoom lens according to the fifth exemplary embodiment includes, in order from the object side, a front group GF having a negative refractive power as a whole and a rear group GB having a positive refractive power as a whole. In the figure, I is an imaging surface.
The front group GF constitutes a first lens group, and is composed of a first subunit G11 and a second subunit G12 in order from the object side.
The first subunit G11 includes a negative meniscus lens L11 having a convex surface directed toward the object side, and a biconcave lens L12.
The second subunit G12 includes a positive meniscus lens L13 ″ having a convex surface facing the object side and a negative meniscus lens L14 ″ ′ having a convex surface facing the object side.

The rear group GB includes, in order from the object side, a second lens group G2 having a positive refractive power as a whole, a third lens group G3 having an aperture stop S and composed of a cemented lens, and a positive refractive power as a whole. And a fourth lens group G4.
The second lens group G2 includes, in order from the object side, a second lens group first subunit G21 having a positive refractive power as a whole and a second lens group second subunit G22.
The second lens group first subunit G21 includes a cemented lens of a biconvex lens L21 and a negative meniscus lens L22 having a concave surface directed toward the object side. The second lens group second subunit G22 includes a cemented lens of a positive meniscus lens L23 having a concave surface directed toward the object side and a biconcave lens L24.
The third lens group G3 includes, in order from the object side, an aperture stop S, and a cemented lens of a biconvex lens L31 and a biconcave lens L32.
The fourth lens group G4 includes, in order from the object side, a biconvex lens L41, a cemented lens of a biconcave lens L42 ′, a biconvex lens L43, a negative meniscus lens L44 ′ having a concave surface facing the object side, and a biconvex lens L45. Has been.

At the time of zooming from the short focal length end to the long focal length end, the front group GF moves to the image side to the intermediate focal length, and the second lens group G2 includes the second lens group first subunit G21 and the second lens group. Integrated with the second subunit G22, the distance from the front group GF is slightly narrowed, and once moved to the image side, then moved slightly to the object side, and the third lens group G3 together with the aperture stop S is moved to the object side. The fourth lens group G4 moves toward the object side so as to narrow the distance from the third lens group G3.
In the zoom lens of Example 5, aspheric surfaces are provided on both surfaces of the negative meniscus lens L11, the image side surface of the biconcave lens L12, the object side surface of the biconvex lens L31, both surfaces of the biconvex lens L41, and the image side surface of the biconvex lens L45. ing.

Next, numerical data of optical members constituting the zoom lens of Example 5 are shown.
Numerical data 5
Short focal length end Intermediate focal length Long focal length end f 7.13 9.90 13.75
FNO 4.06 4.05 4.05
fb 34.35 41.45 51.57
D8 5.87 5.83 5.57
D14 19.00 8.69 2.30
D18 8.37 4.45 1.00

r ₁ = 90.750 (aspherical surface) d ₁ = 2.70 n _d1 = 1.74320 ν _d1 = 49.34
r ₂ = 12.255 (aspherical surface) d ₂ = 14.12
r ₃ = −79.277 d ₃ = 2.00 n _d3 = 1.78800 ν _d3 = 47.37
r ₄ = 28.516 (aspherical surface) d ₄ = 3.70
r ₅ = 24.692 d ₅ = 4.70 n _d5 = 1.80100 ν _d5 = 34.97
r ₆ = 113.998 d ₆ = 2.35
r ₇ = 33.793 d ₇ = 1.80 n _d7 = 1.88300 ν _d7 = 40.76
r ₈ = 17.737 d ₈ = D8
r ₉ = 22.953 d ₉ = 9.50 n _d9 = 1.72825 ν _d9 = 28.46
r ₁₀ = -18.200 d ₁₀ = 1.50 n _d10 = 1.92286 ν _d10 = 18.90
r ₁₁ = −33.426 d ₁₁ = 1.50
r ₁₂ = 279.952 d ₁₂ = 3.80 n _d12 = 1.48749 ν _d12 = 70.23
r ₁₃ = −30.278 d ₁₃ = 1.50 n _d13 = 1.88300 ν _d13 = 40.76
r ₁₄ = 33.190 d ₁₄ = D14
r ₁₅ = ∞ (aperture) d ₁₅ = 1.90
r ₁₆ = 39.153 (aspherical surface) d ₁₆ = 5.20 n _d16 = 1.68893 ν _d16 = 31.07
r ₁₇ = -12.863 d ₁₇ = 1.60 n _d17 = 1.88300 ν _d17 = 40.76
r ₁₈ = 292.764 d ₁₈ = D18
r ₁₉ = 18.154 (aspherical surface) d ₁₉ = 7.60 n _d19 = 1.49700 ν _d19 = 81.54
r ₂₀ = -22.150 (aspherical surface) d ₂₀ = 0.50
r ₂₁ = -221.592 d ₂₁ = 1.50 n _d21 = 1.88300 ν _d21 = 40.76
r ₂₂ = 17.310 d ₂₂ = 8.80 n _d22 = 1.49700 ν _d22 = 81.54
r ₂₃ = -18.616 d ₂₃ = 1.65 n _d23 = 1.88300 ν _d23 = 40.76
r ₂₄ = -213.823 d ₂₄ = 0.50
_{r 25 = 90.085 d 25 = 6.15} n d25 = 1.51633 ν d25 = 64.14
r ₂₆ = -18.197 (aspherical surface) d ₂₆ = fb

Aspheric coefficient surface number K A ₄ A ₆ A ₈ A ₁₀
1 8.0000 2.2064 × 10 ^-6 -9.9726 × 10 ^-10 4.4347 × 10 ^-12 -3.6399 × 10 ^-15
2 -1.2476 -1.8646 × 10 ^-7 7.5733 × 10 ^-8 -2.0013 × 10 ^-10 7.3746 × 10 ^-13
4 0 3.3476 × 10 ^-5 -6.6 100 × 10 ^-8 2.2344 × 10 ^-10 -4.3613 × 10 ^-13
16 0.6192 1.2941 × 10 ^-5 -4.2864 × 10 ^-8 6.6912 × 10 ^-10 -6.0476 × 10 ^-12
19 -2.1983 1.3102 × 10 ^-5 6.3100 × 10 ^-8 -3.6171 × 10 ^-10 -2.7267 × 10 ^-12
20 -2.3606 1.3340 × 10 ^-5 -8.7264 × 10 ^-9 -1.6358 × 10 ^-10 -3.5812 × 10 ^-12
26 -1.1138 -5.9273 × 10 ^-6 1.3632 × 10 ^-8 1.0125 × 10 ^-10 7.2927 × 10 ^-14
IH (image height): 11.14

In each of the above embodiments, the aperture shape when the aperture is open is a circular shape centered on the optical axis.
Next, Table 1 shows the values of the conditional expression parameters in each example.
Table 1
Formula (1) ... 0.18 <1 / (1-dfrw · Φfw + Φw · hrw) <0.30
Formula (2)... 0.5 <| ΦIII / ΦL | <1.7
Formula (3)... 0.45 <| Φu1 / Φfw | <1.0
Formula (4) ...- 0.5 <(r2f-r2r) / (r2f + r2r) <0.2
Formula (5) ... 0.60 <f1_w / IH <0.8 3

  The zoom lens according to the present invention as described above can be used in an imaging apparatus that forms an object image as an imaging optical system and receives the image with an imaging element such as a CCD or a silver salt film to perform imaging. The typical embodiment is shown below.

  FIG. 11 is a schematic configuration diagram showing an example of a single-lens reflex camera using the zoom lens of the present invention as a photographic lens and using a small CCD or C-MOS as an image sensor. In FIG. 11, 1 is a single-lens reflex camera, 2 is a photographic lens, 3 is a mount portion that allows the photographic lens 2 to be detachable from the single-lens reflex camera 1, and a screw-type mount, bayonet-type mount, or the like is used. . In this example, a bayonet type mount is used. Reference numeral 4 denotes an image pickup device surface, 5 denotes a quick return mirror disposed between the lens system on the optical path 6 of the photographing lens 2 and the image pickup device surface 4, and 7 denotes an optical path reflected from the quick return mirror. A finder screen, 8 is a pentaprism, 9 is a finder, and E is an observer's eye (eye point). The zoom lens of the present invention is used as the photographing lens 2 of the single-lens reflex camera 1 having such a configuration.

The image of the subject is formed as an intermediate image on the finder screen 7 through the photographing lens 2 and the quick return mirror 5 and is observed by the pentaprism 8 and the finder 9. Further, at the time of imaging, the quick return mirror 5 jumps up and an image of the subject is formed on the imaging element surface 4 through the photographing lens 2.
As shown in FIG. 12, the diagonal length of the imaging area used for image display and printing after imaging on the imaging element surface 4 is 2IH.

1 is a cross-sectional view along an optical axis showing an optical configuration of a zoom lens according to Example 1 of the present invention, where (a) is a short focal length end, (b) is an intermediate focal length, and (c) is a long focal length end. Indicates the state. FIG. 4 is a diagram illustrating spherical aberration, astigmatism, distortion, and lateral chromatic aberration at the time of focusing at infinity of the zoom lens according to Example 1, where (a) is a short focal length end, (b) is an intermediate focal length, ( c) shows the state at the long focal length end. FIG. 6 is a cross-sectional view along the optical axis showing an optical configuration of a zoom lens according to Example 2 of the present invention, where (a) is a short focal length end, (b) is an intermediate focal length, and (c) is a long focal length end. Indicates the state. FIG. 7 is a diagram illustrating spherical aberration, astigmatism, distortion, and lateral chromatic aberration at the time of focusing at infinity of the zoom lens according to Example 2, where (a) is a short focal length end, (b) is an intermediate focal length, ( c) shows the state at the long focal length end. FIG. 7 is a cross-sectional view along the optical axis showing an optical configuration of a zoom lens according to Example 3 of the present invention, where (a) is a short focal length end, (b) is an intermediate focal length, and (c) is a long focal length end. Indicates the state. FIG. 7 is a diagram illustrating spherical aberration, astigmatism, distortion, and lateral chromatic aberration at the time of focusing at infinity of the zoom lens according to Example 3, where (a) is a short focal length end, (b) is an intermediate focal length, ( c) shows the state at the long focal length end. FIG. 6 is a cross-sectional view along the optical axis showing an optical configuration of a zoom lens according to Example 4 of the present invention, where (a) is a short focal length end, (b) is an intermediate focal length, and (c) is a long focal length end. Indicates the state. FIG. 6 is a diagram showing spherical aberration, astigmatism, distortion, and lateral chromatic aberration at the time of focusing at infinity of the zoom lens according to Example 4, where (a) is a short focal length end, (b) is an intermediate focal length, ( c) shows the state at the long focal length end. FIG. 10 is a cross-sectional view along an optical axis showing an optical configuration of a zoom lens according to Example 5 of the present invention, where (a) is a short focal length end, (b) is an intermediate focal length, and (c) is a long focal length end. Indicates the state. FIG. 10 is a diagram illustrating spherical aberration, astigmatism, distortion, and lateral chromatic aberration at the time of focusing at infinity of the zoom lens according to Example 5, where (a) is a short focal length end, (b) is an intermediate focal length, ( c) shows the state at the long focal length end. 1 is a cross-sectional view showing a schematic configuration of a single-lens reflex camera using a zoom lens as a photographing lens and using a small CCD or C-MOS as an imaging element as an example of an imaging device using a zoom lens according to the present invention. It is explanatory drawing which shows the imaging area used for the image display and printing after imaging in the image pick-up element surface of the camera of FIG.

Explanation of symbols

GF front group (first lens group)
GB Rear group G2 Second lens group G3 Third lens group G4 Fourth lens group I Imaging surface G11 (first lens group) First subunit G12 (first lens group) Second subunit G21 (second lens group) First subunit G22 (second lens group) Second subunit L11 Negative meniscus lens having a convex surface facing the object side L12 Biconcave lens L12 ′ Negative meniscus lens having a convex surface facing the object side L13 Biconcave lens L13 ′ The object side is flat Plano-concave lens with concave image side L13 "Positive meniscus lens with convex surface facing object side L14 Biconvex lens L14 'Positive meniscus lens with convex surface facing object side L14" Biconcave lens L14 "' Negative meniscus lens with convex surface facing object side L15 Negative meniscus lens with concave surface facing the object side L15 'Biconcave lens L15 "Concave surface facing the object side Positive meniscus lens L21 Biconvex lens L22 Negative meniscus lens with concave surface facing the object side L23 Positive meniscus lens with concave surface facing the object side L23 'Biconvex lens L24 Biconcave lens L31 Biconvex lens L32 Biconcave lens L41 Biconvex lens L42 Convex surface on the object side Negative meniscus lens L43 Biconvex lens L44 Biconcave lens L44 'Negative meniscus lens with concave surface facing the object side L45 Biconvex lens L46 Biconvex lens S Aperture stop P Optical path bending prism E Observer's eye LF Optical low-pass filter a Compact camera photography Objective lens Lb Optical path for photographing Le Optical path for finder 1 Single-lens reflex camera 2 Photographing lens 3 Mount part 4 Image sensor surface 5 Quick return mirror 6 Optical path of photographing lens 7 Viewfinder screen 8 Pen Prism 9 Finder

Claims (14)

In order from the object side, a front group having a negative refractive power as a whole, and a rear group having a positive refractive power as a whole Te formed Ttei and during zooming, the front group and rear group Change the air spacing of
The rear group includes, in order from the object side, a second lens group having a positive refractive power as a whole, a third lens group having an aperture stop and a cemented lens, and a second lens group having a positive refractive power as a whole. 4 lens groups, and at the time of zooming, the air spacing of each of the second to fourth lens groups is changed,
Further, the second lens group is composed of a second lens group first subunit and a second lens group second subunit in order from the object side. A configuration in which the air gap between the first group subunit and the second subunit of the second lens group is not changed, or the second lens group has a positive refractive power as a whole in order from the object side. The second lens group first subunit and the second lens group second subunit composed of a negative single lens, and at the time of zooming, the second lens group first subunit and the second subunit The air gap between the second lens group and the second subunit is changed.
A zoom lens whose group interval is changed when zooming is 4 or 5 groups ,
The last lens group arranged closest to the image plane of the rear group includes a cemented lens including three lenses having two cemented surfaces, and the positive lens is at least on the object side and the image side of the cemented lens. It is configured by arranging one piece ,
Zoom lens characterized that you satisfy the following condition (2).
0.5 <| ΦIII / ΦL | <1.7 (2)
Where ΦIII is the refractive power of the cemented lens composed of the three lenses having the two cemented surfaces, and ΦL is the refractive power of the final lens group. The zoom lens according to claim 1, wherein the following conditional expression (1) is satisfied.
0.18 <1 / (1-dfrw × Φfw + Φw × hrw) <0.30 (1)
Where Φw is the refractive power of the entire system at wide angle, Φfw is the refractive power of the front group at wide angle, dfrw is the distance between the main point of the front group and the main point of the rear group at wide angle, and hrw is after the wide angle This is the rear principal point position of the group. The zoom lens according to claim 1, wherein the following conditional expression (2 ′) is satisfied .
0.7 <| ΦIII / ΦL | <1.5 (2 ′)   The front group includes, in order from the object side, a first negative meniscus lens having a convex surface facing the object side and a second negative meniscus lens having a convex surface facing the object side having at least one aspheric surface. 4. The zoom lens according to claim 1, comprising a subunit and a second subunit having at least one positive lens and at least one negative lens. 5. . The second lens group includes, in order from the object side, a second lens group first subunit having a positive refractive power as a whole and a second lens group second subunit composed of a negative single lens. ,
5. The zoom lens according to claim 1 , wherein an air space between the second subunit of the second lens group and the second subunit of the second lens group is changed during zooming. . The final lens group includes, in order from the object side , a positive single lens having at least one aspherical surface, a cemented lens having two diverging surfaces composed of a negative lens, a biconvex lens, and a negative lens, and a positive single lens. The zoom lens according to claim 1, wherein the zoom lens is configured as follows . The zoom lens according to claim 1 , wherein the following conditional expression (5) is satisfied .
0.60 <f1_w / IH <0.83 (5)
However, f1_w is the focal length at the short focal length end, and IH is the image height. A zoom lens according to any one of 請 Motomeko 1-7, an imaging apparatus characterized by including an imaging portion for determining an imaging region arranged on the image side. The zoom lens according to claim 4 , wherein the following conditional expression (3) is satisfied .
0.45 <| Φu1 / Φfw | <1.0 (3)
Where Φu1 is the refractive power of the first subunit, and Φfw is the refractive power of the front group at a wide angle . The zoom lens according to any one of claims 1 to 9, wherein the following conditional expression (4) is satisfied.
−0.5 <(r2f−r2r) / (r2f + r2r) <0.2 (4)
Here, r2f is the radius of curvature of the lens surface closest to the object side of the second lens group, r2r is the radius of curvature of the lens surface closest to the image side of the second lens group, and 0 <r2f and 0 <r2r. The zoom lens according to claim 2 , wherein the following conditional expression (1 ′) is satisfied.
0.20 <1 / (1-dfrw × Φfw + Φw × hrw) <0.25 (1 ′)
Where Φw is the refractive power of the entire system at wide angle, Φfw is the refractive power of the front group at wide angle, dfrw is the distance between the main point of the front group and the main point of the rear group at wide angle, and hrw is after the wide angle This is the rear principal point position of the group. The zoom lens according to claim 1, wherein the following conditional expression (3 ′) is satisfied.
0.5 <| Φu1 / Φfw | <0.9 (3 ′)
Where Φu1 is the refractive power of the first subunit, and Φfw is the refractive power of the front group at a wide angle. The zoom lens according to claim 1 , wherein the following conditional expression (4 ′) is satisfied.
−0.4 <(r2f−r2r) / (r2f + r2r) <0.1 (4 ′)
Here, r2f is the radius of curvature of the lens surface closest to the object side of the second lens group, r2r is the radius of curvature of the lens surface closest to the image side of the second lens group, and 0 <r2f and 0 <r2r . The zoom lens according to claim 1, wherein the following conditional expression (5 ′) is satisfied.
0.63 <f1_w / IH <0.75 (5 ′)
However, f1_w is the focal length at the short focal length end, and IH is the image height .